1. Field
Systems, apparatuses and methods consistent with exemplary embodiments relate to an audio signal processing system and an echo signal removing method thereof, and more particularly, to an audio signal processing system to remove an echo signal that is output from a speaker and is input into a microphone and an echo signal removing method thereof.
2. Description of the Related Art
Due to developments in communication technology and sound technology, a voice call system that allows call and conversation to be performed between speakers which are located apart from each other has been widely used. Also, in recent years, voice recognition technology that controls electronic apparatuses by using a user's voice has been widely used.
The voice call system and electronic apparatuses includes at least one speaker and at least one microphone, respectively. Particularly, in the apparatuses including both the speaker and microphone, a voice signal output from the speaker may be received by the microphone of the same apparatuses. If the operation is repeated in a cycle, an echo phenomenon that a voice output from the speaker is received through the microphone with a voice that a user utters may occur.
As a result, in the case of the acoustic system to perform call and conversation between speakers that are spaced apart from each other, a howling phenomenon that a user's voice sounds like an echo may occur. Also, in the case of the electronic apparatus that is controlled by the user's voice, a misrecognition phenomenon that the electronic apparatus does not properly recognize the voice uttered by the user may occur.
Recently, in order to prevent the echo phenomenon, echo cancellation technology is applied to the apparatuses equipped with both the speaker and the microphone.
Particularly, the echo cancellation technology is applied to an audio signal processing system which uses an adaptive filter. The system using the adaptive filter obtains impulse response characteristics with respect to passing sound (echo path) between the speaker and the microphone, and then, records the impulse response in an input signal of a sound that will be output from the speaker, thereby outputting echo signal components. Then, the audio signal processing system can receive the voice signal from which the echo signal is removed by subtracting the echo signal components from the voice signal received by the microphone.
However, in the case of the system in which the beginning of the echo path is unknown, bulk delay may occur. The bulk delay may be caused due to different buffering structures of the audio recording hardware and software, or unknown positions of the unknown speakers and microphones. If this bulk delay is not properly compensated, a problem that the echo signal is not properly removed may occur.
Accordingly, ways that compensate the bulk delay so as to cancel the echo signals are needed.